Energy absorbing steering column

DETAILED DESCRIPTION This invention is a new and improved collapsible, energy absorbing steering column for automotive vehicles.
The collapsible steering column according to this invention has a plurality of primary roll deformers in an annulus between telescopically overlapped upper and lower mast jackets of the column, a plurality of secondary roll deformers outside the axial extent of the overlap between the mast jackets, and means for maintaining the relative positions of the primary and secondary roll deformers during collapse of the steering column so that the secondary roll deformers become operatively lodged in the annulus between the mast jackets after a predetermined axial collapse to initiate secondary or staged energy absorption.
In a preferred embodiment of the steering column according to this invention, the primary and secondary roll deformers are loosely supported in respective primary and secondary parts of a plastic sleeve, the primary part of the sleeve being disposed in the overlap between the upper and lower mast jackets in the normal, uncollapsed condition of the steering column and the secondary part being outside the overlap.
In a modified embodiment of the steering column according to this invention, the plastic sleeve has two secondary parts on opposite sides of the primary part so that secondary roll deformers enter the overlap between the mast jackets from both ends of the overlap.